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When a noise-exposed worker’s audiogram crosses the OSHA 300 Log recordability threshold — an average hearing level of 25 dB or more at 2000, 3000, and 4000 Hz — the employer does not automatically record it. First, work-relatedness must be determined. This is one of the most consequential and least clearly understood steps in OSHA hearing conservation compliance. Get it right and you have a defensible record. Get it wrong — by recording non-occupational cases or by asserting non-occupational causation without documentation — and you either inflate your OSHA log unnecessarily or expose yourself to citation and WC liability.
Soundtrace routes every audiogram meeting the recordability threshold to our licensed audiology team for professional supervisor review, with work-relatedness documentation integrated into the audiometric record.
OSHA 1904.10 requires both conditions to be met before a case is recordable: (1) the audiogram shows ≥25 dB average HL at 2/3/4 kHz, and (2) the case is work-related under 1904.5. Meeting condition 1 does not automatically satisfy condition 2. Work-relatedness must be evaluated separately for every case that crosses the audiometric threshold.
OSHA’s occupational hearing loss recordkeeping rule at 29 CFR 1904.10 requires a two-part analysis. The first part is audiometric: does the employee’s current audiogram show an average hearing level of 25 dB HL or more at 2000, 3000, and 4000 Hz? This calculation uses no age correction and is performed per ear. The second part is causal: is the hearing loss work-related under the general work-relatedness standard at 29 CFR 1904.5?
The audiometric threshold is objective and mathematical. Work-relatedness is a judgment that requires professional evaluation. Most employers understand the first part; the second part is where programs frequently err.
| Step | Question | Standard | Age Correction? |
|---|---|---|---|
| 1. Audiometric threshold | Does the audiogram show ≥25 dB HL average at 2/3/4 kHz? | 1904.10(a) | No — prohibited |
| 2. Work-relatedness | Is the hearing loss work-related? | 1904.5 | Not applicable |
| Result: Recordable | Both conditions met? | 1904.10 | — |
| Result: Not recordable | Either condition not met? | 1904.10 | — |
Under 29 CFR 1904.5(a), a case is work-related if an event or exposure in the work environment either caused or contributed to the condition, or significantly aggravated a pre-existing condition. For occupational hearing loss, work-relatedness is presumed when the employee is enrolled in the hearing conservation program — meaning the employer has already determined the employee is exposed to hazardous noise. This presumption is rebuttable, but the burden of rebuttal is on the employer.
1904.5(b)(2) provides that an employer does not need to record a case if the employer can establish that the work environment was not a contributing factor. For hearing loss, this means providing evidence that the loss has a non-occupational cause that is independently sufficient to explain the audiometric findings — and that occupational noise exposure did not contribute.
Work-relatedness is presumed, not proven by the employee. An employer who wants to classify a hearing loss case as non-work-related must affirmatively document why. Simply noting “employee reports loud music exposure” or “employee is a hunter” without medical evaluation does not satisfy this burden. The NHCA guidelines are explicit: non-occupational assertions must be substantiated.
OSHA 1904.5(b)(3) allows the employer to obtain a medical opinion from a physician or other licensed health care professional (PLHCP) to assist with work-relatedness determinations. The employer may rely on that opinion if it is reasonable. If two medical opinions conflict, the employer may follow the second opinion if it is more detailed and specific.
In hearing conservation programs, the professional supervisor (PS) of the audiometric testing program — typically a licensed audiologist or physician — is the appropriate professional to make or support work-relatedness determinations. The PS reviews the audiometric record, the employee’s noise exposure history, the audiometric pattern, and any available medical history to form an opinion. This opinion is then documented in the audiometric record.
Employers who do not have a PS reviewing their audiograms are not positioned to make defensible work-relatedness determinations for cases at or near the recordability threshold. The determination requires clinical judgment, not administrative policy.
The National Hearing Conservation Association has published guidelines for professional supervisors making work-relatedness determinations for OSHA 300 Log purposes. These guidelines, while not OSHA regulations, represent the professional standard of care for audiologists and physicians making these determinations and are widely referenced in WC proceedings.
The NHCA’s primary principle is that unless there are clear and cogent reasons why the loss is entirely unrelated to the work environment, it should be considered work-related and recordable. This sets a high bar for non-occupational determinations. The guidelines specifically caution against:
The PS is not an advocate for the employer — they are an independent professional making a clinical judgment. A PS who consistently determines cases non-work-related without documentation is creating liability for both the employer (if the determination is wrong) and themselves (professional discipline risk). The most defensible PS determinations are specific, documented, and based on identified non-occupational causes rather than on the absence of a definitive occupational cause.
For a non-work-related determination to be defensible, a specific non-occupational cause must be identified, documented, and assessed as sufficient to independently explain the audiometric findings. Generalized recreational noise exposure history is not sufficient by itself. The following non-occupational causes can support a non-work-related determination when properly documented:
Classical occupational NIHL is bilateral and shows a notch at 3000–6000 Hz with relative preservation of lower frequencies. Hearing loss that is predominantly low-frequency, unilateral without explanation by exposure geometry, or shows a pattern inconsistent with noise damage may indicate a non-occupational etiology. The PS should document specifically how the audiometric pattern departs from expected NIHL and what that suggests about causation.
Confirmed diagnoses of otosclerosis, Meniere’s disease, acoustic neuroma, autoimmune inner ear disease, or chronic otitis media are non-occupational causes that can independently explain hearing loss. Medical documentation of the diagnosis and an explanation of how it accounts for the audiometric findings is required.
Certain medications — aminoglycoside antibiotics, loop diuretics, some chemotherapy agents — are ototoxic and can cause sensorineural hearing loss. If the employee has a documented history of ototoxic medication use at levels sufficient to cause the observed loss, this may support a non-occupational determination. A physician opinion on the plausibility of the medication history as a causal explanation is required.
A documented sudden hearing loss following a non-occupational acoustic event (gunshot, explosion, concert, sporting event) can support a non-occupational determination for the affected ear. The timing and audiometric pattern must be consistent with the event.
The following do not, by themselves, support a non-work-related determination: recreational noise history without assessment of dose; the employee’s own report that they think their hearing loss is not from work; the employer’s desire to keep the 300 Log clean; or the fact that the employee is older and “expected” to have some hearing loss. Each requires additional documentation and medical assessment.
An employer who makes a non-work-related determination without a supporting PLHCP or PS opinion has no defensible basis for that determination if it is later challenged. OSHA’s recordkeeping standard explicitly contemplates medical input for hearing loss cases. Employers who assert non-occupational causation based solely on the safety manager’s review are exposed to citation under 1904.10.
This is prohibited by 1904.10(a). Employers who use age-corrected thresholds to evaluate whether the 25 dB threshold is met are miscalculating the recordability determination. The 25 dB threshold is measured from audiometric zero, without adjustment.
Long tenure in a noise-exposed role is evidence of occupational exposure, not of non-occupational causation. Age-related hearing loss in a noise-exposed worker does not make the loss non-work-related — the occupational noise contributed to or aggravated the condition regardless of the age component.
A determination — work-related or not — that is not documented does not exist for compliance purposes. The audiometric record should contain the date of the determination, who made it, the basis for it, and the resulting recording decision. This documentation should be retained for the duration of employment.
Under 1904.10(b)(5), employers have up to 30 days after receiving the results of an audiometric test to determine work-relatedness and decide whether to record the case. The 300 Log entry date is the date the audiogram was taken if the determination is made within 30 days, or the date the determination is made if longer than 30 days.
This 30-day window is intended to allow time for the PS or PLHCP to review the audiogram, obtain any necessary medical history, and form a supported opinion. It is not a period during which no action is taken — the PS review should be initiated promptly so that the 30 days is used for evaluation, not administrative delay.
▶ Bottom line: The 30-day clock begins when the employer receives the audiometric test results. Use it to complete PS review and document the determination. Do not wait until day 29 to start the process.
OSHA work-relatedness determinations and WC compensability are separate legal questions with separate standards. A case determined non-work-related for OSHA 300 Log purposes is not automatically denied in WC proceedings — and a case recorded on the 300 Log is not automatically compensable in WC. These are parallel systems with different evidentiary standards and legal frameworks.
That said, a consistently documented audiometric record — including PS work-relatedness determinations with specific reasoning — is the factual foundation for WC apportionment arguments. Employers whose PS reviews are specific, timely, and well-documented are significantly better positioned to defend WC claims than those whose records contain only data without clinical interpretation.
Soundtrace routes audiograms meeting the recordability threshold to licensed audiologist review, with work-relatedness documentation integrated into the audiometric record — so the 30-day clock never catches you unprepared.
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